Ling 566 Feb 2, 2006 Lexical Types Overview • Motivation for lexical hierachy • Default inheritance • Tour of the lexeme hierarchy • The Case Constraint • pos vs. lexeme • Guest appearance by Will 2 Motivation • We've streamlined our grammar rules... • ...by stating some constraints as general principles • ...and locating lots of information in the lexicon. • Our lexical entries currently stipulate a lot of information that is common across many entries and should be stated only once. • Examples? • Ideally, particular lexical entries need only give phonological form, the semantic contribution, and any constraints truly idiosyncratic to the lexical entry. 3 Lexemes and Words • Lexeme: An abstract proto-word which gives rise to genuine words. We refer to lexemes by their ‘dictionary form’, e.g. ‘the lexeme run’ or ‘the lexeme dog’. • Word: A particular pairing of form and meaning. Running and ran are different words 4 Lexical Types & Lexical Rules • Lexemes capture the similarities among run, runs, running, and run. • The lexical type hierarchy captures the similarities among run, sleep, and laugh, among those and other verbs like devour and hand, and among those and other words like book. Q: What do devour and book have in common? A: The SHAC • Lexical rules capture the similarities among runs, sleeps, devours, hands,... 5 Default Inheritance Q: Why do we have default inheritance? A: Generalizations with exceptions are common: • Most nouns in English aren't marked for CASE, but pronouns are. • Most verbs in English only distinguish two agreement categories (3sing and non-3sing), but be distinguishes more. • Most prepositions in English are transitive, but here and there are intransitive. • Most nominal words in English are 3rd person, but some (all of them pronouns) are 1st or 2nd person. • Most proper nouns in English are singular, but some (mountain range names, sports team names) are plural. 6 Default Inheritance, Technicalities and one of its then the ARG-ST If a type says subtypes says value of instances of ARG-ST / < NP >, ARG-ST < >, the subtype is < >. then this subtype can have no and one of its If a type says instances, since they subtypes says ARG-ST < NP >, would have to ARG-ST < >, satisfy contradictory constraints. 7 Default Inheritance, More Technicalities • If a type says MOD / < S >, and one of its subtypes says MOD <[SPR < NP> ] >, then the ARG-ST value of instances of the subtype is HEAD / verb MOD SPR NP $ * % & COMPS / ! " • That is, default constraints are ‘pushed down’ 8 Question on Default Inheritance Q: Can a grammar rule override a default constraint on a word? A: No. Defaults are all ‘cached out’ in the lexicon. • Words as used to build sentences have only inviolable constraints. 9 Our Lexeme Hierarchy synsem [SYN, SEM] lexeme expression [ARG-ST] word phrase [ARG-ST] infl-lxm const-lxm . pn-lxm pron-lxm . adj -lxm conj -lxm det-lxm predp-lxm argmkp-lxm verb-lxm cn-lxm siv-lxm piv-lxm tv-lxm cntn-lxm massn-lxm stv-lxm dtv-lxm ptv-lxm 10 Functions of Types • Stating what features are appropriate for what categories • Stating generalizations • Constraints that apply to (almost) all instances • Generalizations about selection -- where instances of that type can appear 11 Every synsem has the features SYN and SEM synsem [SYN, SEM] lexeme expression [ARG-ST] word phrase [ARG-ST] infl-lxm const-lxm . pn-lxm pron-lxm . adj -lxm conj -lxm det-lxm predp-lxm argmkp-lxm verb-lxm cn-lxm siv-lxm piv-lxm tv-lxm cntn-lxm massn-lxm stv-lxm dtv-lxm ptv-lxm 12 No ARG-ST on phrase synsem [SYN, SEM] lexeme expression [ARG-ST] word phrase [ARG-ST] infl-lxm const-lxm . pn-lxm pron-lxm . adj -lxm conj -lxm det-lxm predp-lxm argmkp-lxm verb-lxm cn-lxm siv-lxm piv-lxm tv-lxm cntn-lxm massn-lxm stv-lxm dtv-lxm ptv-lxm 13 A Constraint on infl-lxm: the SHAC synsem [SYN, SEM] lexeme expression [ARG-ST] word phrase [ARG-ST] infl-lxm const-lxm . pn-lxm pron-lxm . adj -lxm conj -lxm det-lxm predp-lxm argmkp-lxm verb-lxm cn-lxm siv-lxm piv-lxm tv-lxm cntn-lxm massn-lxm stv-lxm dtv-lxm ptv-lxm 14 A Constraint on infl-lxm: the SHAC VAL SPR [AGR 1 ] infl-lxm : SYN $ % &' HEAD [ AGR 1 ] 15 Constraints on cn-lxm synsem [SYN, SEM] lexeme expression [ARG-ST] word phrase [ARG-ST] infl-lxm const-lxm . pn-lxm pron-lxm . adj -lxm conj -lxm det-lxm predp-lxm argmkp-lxm verb-lxm cn-lxm siv-lxm piv-lxm tv-lxm cntn-lxm massn-lxm stv-lxm dtv-lxm ptv-lxm 16 Constraints on cn-lxm noun HEAD $AGR [PER 3rd]% SYN HEAD det VAL SPR ! " cn-lxm : INDEX i $ % MODE / ref SEM INDEX i $ % ARG-ST !X" ⊕ /! " 17 Formally Distinguishing Count vs. Mass Nouns synsem [SYN, SEM] lexeme expression [ARG-ST] word phrase [ARG-ST] infl-lxm const-lxm . pn-lxm pron-lxm . adj -lxm conj -lxm det-lxm predp-lxm argmkp-lxm verb-lxm cn-lxm siv-lxm piv-lxm tv-lxm cntn-lxm massn-lxm stv-lxm dtv-lxm ptv-lxm 18 Formally Distinguishing Count vs. Mass Nouns cntn-lxm : SYN VAL SPR ! [COUNT +] " ! & " # $% massn-lxm : SYN VAL SPR ! [COUNT −] # ! & " # $% 19 Constraints on verb-lxm synsem [SYN, SEM] lexeme expression [ARG-ST] word phrase [ARG-ST] infl-lxm const-lxm . pn-lxm pron-lxm . adj -lxm conj -lxm det-lxm predp-lxm argmkp-lxm verb-lxm cn-lxm siv-lxm piv-lxm tv-lxm cntn-lxm massn-lxm stv-lxm dtv-lxm ptv-lxm 20 Constraints on verb-lxm verb SYN $HEAD % verb-lxm : SEM MODE prop $ % ARG-ST / ! NP, ... " 21 Subtypes of verb-lxm verb-lxm siv-lxm piv-lxm tv-lxm stv-lxm dtv-lxm ptv-lxm • verb-lxm: [ARG-ST / < NP, ... >] • siv-lxm: [ARG-ST / < NP >] • piv-lxm: [ARG-ST / < NP, PP >] • tv-lxm: [ARG-ST / < NP, NP, ... >] • stv-lxm: [ARG-ST / < NP, NP, >] • dtv-lxm: [ARG-ST / < NP, NP, NP >] • ptv-lxm: [ARG-ST22 / < NP, NP, PP >] Proper Nouns and Pronouns synsem [SYN, SEM] lexeme expression [ARG-ST] word phrase [ARG-ST] infl-lxm const-lxm . pn-lxm pron-lxm . adj -lxm conj -lxm det-lxm predp-lxm argmkp-lxm verb-lxm cn-lxm siv-lxm piv-lxm tv-lxm cntn-lxm massn-lxm stv-lxm dtv-lxm ptv-lxm 23 Proper Nouns and Pronouns noun SYN HEAD PER 3rd AGR NUM / sg pn-lxm: $ % SEM MODE ref ARG-S)T / ! " * SYN $HEAD noun% pron-lxm: SEM MODE / ref $ % ARG-ST ! " 24 The Case Constraint An outranked NP is [CASE acc]. • object of verb ✓ • second object of verb ✓ • object of argument-marking preposition ✓ • object of predicational preposition (✓) 25 The Case Constraint, continued An outranked NP is [CASE acc]. • Subjects of verbs • Should we add a clause to cover nominative subjects? • No. We expect them to leave. (Chapter 12) • Lexical rules for finite verbs will handle nominative subjects. • Any other instances of case marking in English? • Case systems in other languages? No: The Case Constraint is an English-specific constraint. 26 Apparent redundancy • Why do we need both the pos subhierarchy and lexeme types? • pos: • Applies to words and phrases; models relationship between then • Constrains which features are appropriate (no AUX on noun) • lexeme: • Generalizations about combinations of constraints 27 Overview • Motivation for lexical hierachy • Default inheritance • Tour of the lexeme hierarchy • The Case Constraint • pos vs. lexeme • Guest appearance by Will 28.